Cold hardiness & minimum temperature

Is Licorice Fern (Polypodium glycyrrhiza)cold hardy? Hardiness zone & min temp

Also called Licorice Fern, Licorice Root Fern.

More about licorice fern

About Licorice Fern

Polypodium glycyrrhiza · also called Licorice Fern, Licorice Root Fern · houseplant

Licorice fern is a small epiphytic Pacific Northwest native named for its sweet-tasting rhizomes. It naturally grows on mossy trunks and rocks, summer-dormant and winter-active. Indoors it wants cool, bright-indirect light, steady moisture, and high humidity. Give it a loose, bark-rich epiphytic mix and expect it to slow or drop fronds through warm, dry months.

Cold limit: USDA 6-9 (outdoors); a cool-room houseplant elsewhere · RHS H5 (7-18°C)

What licorice fern's hardiness rating actually means

Yes — licorice fern is genuinely cold hardy. Rated RHS H5 and USDA 6-9 (outdoors); a cool-room houseplant elsewhere, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 6-9 (outdoors); a cool-room houseplant elsewhere — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

Minimum survivable temperature is roughly about −15 to −10 °C. Licorice Fern is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for licorice fern as it gets too cold:

It tolerates winter lows to about −15 to −10 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can licorice fern go outside or overwinter — and where?

Plant it out within USDA 6-9 (outdoors); a cool-room houseplant elsewhere and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when licorice fern can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Licorice Fern hardiness — frequently asked questions

Is licorice fern cold hardy?

Yes — licorice fern is genuinely cold hardy. Rated RHS H5 and USDA 6-9 (outdoors); a cool-room houseplant elsewhere, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Licorice Fern is hardy across USDA 6-9 (outdoors); a cool-room houseplant elsewhere; it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature licorice fern can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Licorice Fern is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is licorice fern?

Licorice Fern is rated USDA 6-9 (outdoors); a cool-room houseplant elsewhere and RHS H5 — Hardy in most of the UK and in cold winters.

Can licorice fern survive winter outside?

Plant it out within USDA 6-9 (outdoors); a cool-room houseplant elsewhere and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to licorice fern below its minimum temperature?

It tolerates winter lows to about −15 to −10 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.